In general, when an elevator car is reciprocally moved up and down by elevator wire ropes suspended to the elevator car, tensional imbalance may occur among the elevator wire ropes.
For this reason, the tensional imbalance of the elevator wire ropes is periodically managed and inspected. In spite of the periodic inspection and management for the elevator wire ropes, since the tensional imbalance of the elevator wire ropes may occur in real time depending on the temperature of the place where the elevator car is installed and the operation frequency of the elevator car, the tensional imbalance may continue until the next inspection.
Such a tensional imbalance causes the eccentric abrasion of pulleys, so there is difference in the number π of the pulleys. The difference in the number π of the pulleys may cause difference in the travel distance of each elevator wire rope, so a slip may occur in the elevator wire ropes when driving the pulleys, causing longitudinal and transverse vibrations. These longitudinal and transverse vibrations may be directly applied to the elevator car, so that the elevator car may be subject to the longitudinal and transverse vibrations.
For this reason, the elevator car may be damaged, the life span of the elevator car may be shortened, and the riding comport of the elevator car may be degraded.